JPH01145059A - Decayed tooth detector applying irradiation with laser beam - Google Patents

Abstract

PURPOSE:To certainly and safely detect a decayed tooth within a short time, by detecting the difference in optical characteristic between decayed dentine and healthy dentine against a laser beam. CONSTITUTION:Laser beam high in the selective absorptivity to a decayed tooth and having proper dentine permeability is generated from a laser beam irradiation device 1 to irradiate a tooth D. The temp. of the oculusal surface of the tooth D being the region irradiated with laser beam is measured by a surface temp. detector 3 composed of a radiation thermometer or infrared sensor. Further, a transmitted light detector 2 is arranged to the side surface of the tooth D in a non-contact state to detect transmitted light. The outputs of these detectors 2, 3 are compared with and investigated to make it possible to detect the decayed tooth.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a device for detecting cavities in teeth, that is, cavities.

(Prior Art) Detection and diagnosis of dental caries is the most important and indispensable thing in dental treatment, and diagnosis has conventionally been generally performed using X-ray photographs.

(Problems to be Solved by the Invention) However, there is a risk that X-rays may have various undesirable effects on living tissues, and therefore, from the standpoint of safety, the conditions for conducting examinations are becoming stricter. Moreover, it has been difficult to detect early caries even with X-ray examination.

This invention was made in view of the above two circumstances, and utilizes the difference in the optical properties of carious tooth material and healthy tooth material with respect to laser light to emit a weak laser beam that does not cause tissue damage or pain. The object of the present invention is to provide a caries detection device using laser light irradiation, which can reliably and safely detect caries in an extremely short period of time by irradiating the tooth with laser light.

(Means for Solving the Problems) In order to achieve the above object, the caries detection device according to the present invention irradiates a tooth with a laser beam from a laser beam irradiation device and detects the reflected light from the irradiation surface. It is characterized by a combination of at least one of a reflected light detector or a surface temperature detector that detects the temperature of the irradiated surface, and a transmitted light detector that detects transmitted light from the tooth surface other than the irradiated part.

(Function) According to the present invention, when a laser beam is irradiated to the oro-oral surface of the tooth using a laser beam irradiation device and the optical characteristics of the carious tooth substance and the healthy tooth substance are different, the laser beam is reflected off the porcelain surface and the laser beam on the tooth substance. The absorption and transmission of light differs between healthy teeth and carious teeth. For example, when a laser beam such as a 1YAG laser or a semiconductor laser is selectively irradiated onto a carious tooth with a high absorption rate and moderate penetration, the reflection on the oral chiasm plane and the transmission from the lateral side will be affected by healthy teeth. In case! ,I2
On the other hand, the temperature of the +1 intersecting surface is much higher than that of teeth, but in the case of carious teeth, the cavity absorbs the laser beam efficiently, so the temperature of the south surface rises much more than in the case of healthy teeth. Since penetration into the tooth structure is suppressed, the amount of light transmitted to the sides is much smaller than in the case of healthy teeth.

It is possible to detect cavities by comparing and examining the differences in optical properties such as reflection, transmission, and surface temperature between healthy teeth and cavities when irradiated with laser light using two or more corresponding detectors. It is.

(Example) Embodiments of the present invention will be described below based on the drawings.

First Example (See Figure 1) This first example is for detecting the surface temperature of the tooth and the transmitted light from the side surface of the tooth. Laser beams such as Nd-YAG lasers that selectively target caries have a high absorption rate and moderate penetration into the tooth structure. 2 is a surface temperature detector, which uses a radiation thermometer or an infrared sensor to measure the temperature of the fused surface of the teeth, which is the irradiated area.

3 is a transmitted light detector, which uses a laser light sensor such as a thermocouple element whose surface has been processed to increase the absorption efficiency of laser light, and is placed non-contact on the side of the mD. Then, the transmitted light lb is detected.

Second Embodiment (See Figure 2) This second embodiment is for detecting the reflection from the interoral surface and the transmitted light from the side surfaces of the teeth. 1 is a laser beam irradiation device, and 3 is a transmitted light detector. , these are the same as in the case of the L-disappeared first embodiment. 4 is a reflected light detector, which, like the transmitted light detector 3 above, uses a laser light sensor such as a thermocouple element whose surface has been processed to have a high absorption rate for laser light. The reflected light 1c from one intersection plane is detected.

Third Embodiment (Illustration omitted) This third embodiment uses the three types of detectors 2, 3.4 and laser beam irradiation device l shown in ``-Make 1 and 2nd Embodiment''. This device improves the detection results of occlusal surface temperature, reflected light, and transmitted light to the side. As shown in FIG. 3, an integrating sphere 6 configured to concentrate transmitted laser light and reflected laser light at approximately one point using a hemispherical or partially cut spherical reflector plate 5 is also used. By arranging the transmitted light detector 3 or the reflected light detector 4 at the focal point, it is possible to reduce the loss of sensitive light and perform predetermined detection with extremely high sensitivity.

Furthermore, the detection results by the Kitami transmitted light detector 3 and the reflected light detector 4 may be recorded on a recorder equipped with a POC mechanism on the same time axis, or two-dimensional observation using a CCD camera may also be used.

(Test example) Next, a test example conducted by the present inventor will be described in detail.

(1) Test method (1)-1 Method based on the above-mentioned first example As shown in Fig. 4, a human extracted tooth that was sterilized and stored in water was used as the specimen, and the tooth was oriented toward the Ekodai surface. YAG laser-1 (
The temperature of the occlusal surface of the teeth (S
To) is the operating wavelength band or 7~llILm radiation thermometer 2
On the other hand, the central part of the side surface of the tooth is coated with 0, which has a surface processed to have a high absorption rate for near-infrared laser light.
Sensor 3 using F+smφ sheath type thermocouple element
is placed in a non-contact manner, and the transmitted laser light (TTs) from the side surface of the teeth is converted into heat for measurement.

Incidentally, the irradiation conditions using the YAG laser 1 were set as follows.

Tip output P: lOW, irradiation distance L: 10mm.

Irradiation diameter D: 2.8n11. Power density PD: 162w/c
m2. Irradiation time T: 0.2 seconds (1)-2 In the method (1)-1 based on the second embodiment, as shown in FIG. A sensor 4 using a 0.51φ sheathed thermocouple whose surface has been processed to have a high absorption rate for laser light is placed above the irradiated surface (occlusal surface) to measure the reflected light from the laser irradiated surface. do.

, j ki 1 χ &j', lk 3 L4 t+ノ
- 10 is of course 4 points.

(2) Test results (2)-1 Results when using the method (1)-1 In the case of healthy teeth, as shown in gS5 diagram (A).

The surface temperature (STo) does not increase much, only 1°C at most, and its peak appears 1 second after laser irradiation and plowing. In addition, transmitted light from the side (T'T
s) rises rapidly at the same time as the laser irradiation and falls at the same time as the irradiation ends.

On the other hand, in the case of cavities and teeth, as shown in Figure 6 (8), the temperature at the zero-crossing surface (STo) rises rapidly at the same time as laser irradiation, reaches a peak after irradiation, and reaches a temperature of approximately 15°C. shows an increase in Furthermore, although the transmitted light (TTs) from the side surface rises with the laser irradiation, its rise time is very small, and the thermocouple reading was about 215 for a healthy tooth.

(2,)-2 (1)-2 Results When using the method of , transmitted light from the side (TT
s) are both significantly larger than those in the case of tooth decay (Fig. 7(B)).

(2)-3 Another test example In the above test example, on the tooth surface determined to be carious, P: IO
W, L: 40 [1111, D: 81111. PD: 20
w/c*2. T: When a radiation thermometer was scanned along the tooth surface while continuously irradiating laser light for 5 seconds, a temperature distribution curve as shown in FIG. 8 was obtained. As can be seen, caries appears as a high temperature pattern.

(3) Conclusions from the test Since YAG laser light scatters and penetrates within the teeth, the surface temperature when irradiated with this on the tooth shows a change that is different from that in the case of conductive heating. That is, in the case of healthy teeth, the temperature rise on the surface of the irradiated part is small, but there is a considerable amount of light transmitted to the side surfaces.

On the other hand, in the case of cavities, the temperature rise on the surface of the irradiated area due to laser irradiation is much more pronounced than in healthy teeth, or there is little penetration of the laser to the sides.

The reaction described above is extremely sensitive.1 For example, in the case of YAG laser light, it is possible to distinguish between carious teeth and healthy teeth even with weak laser light irradiation that does not cause tissue damage or pain at 162 w/cv" or less. It turned out that there was something.

(Effects of the Invention) As is already clear from the above embodiments and test examples, according to the present invention, healthy teeth and carious teeth have different optical characteristics with respect to laser light, and their optical characteristics Taking advantage of the extremely sensitive characteristic response, cavities can be detected safely and reliably in an extremely short period of time using weak laser irradiation that does not cause unfavorable effects on living organisms such as tissue damage or pain. I can do it.

In addition, it is possible to detect early caries, which is difficult to detect using conventional X-ray photography, which greatly contributes to improving dental treatment.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the main part showing the first embodiment of the present invention, Fig. 2 is a block diagram of the main part showing the second embodiment, and Fig. 3 is a device for improving the measurement sensitivity of this measurement. Structure diagram, Figure 4,
Figure 5 is an explanatory diagram of the test procedure, Figures 6 (A) and (B) are graphs showing the test results based on the first example, and Figure 7 (A).
) and (B) are graphs showing test results based on the second example, and FIG. 8 is a graph showing another test result. (Explanation of symbols) l... Laser light irradiation device (Nd-YAG laser,
semiconductor laser), 2... surface temperature detector (radiation thermometer), 3... transmitted light detector (thermocouple sensor), 4-
... Reflected light detector (thermocouple sensor), 6... Integrating sphere. Figure 1 Figure 2 Figure 4: Reflection stack Figure 3 Figure 4 Figure 5 Figure 7

Claims (5)

[Claims] (1) A laser beam irradiation device irradiates the tooth with laser light, and at least one of a reflected light detector that detects the reflected light from the irradiated surface or a surface temperature detector that detects the surface temperature of the tooth, and a A caries detection device that applies laser light irradiation, characterized in that it is combined with a transmitted light detector that detects transmitted light from tooth surfaces. (2) The laser beam irradiation device according to claim 1, wherein the laser beam irradiation device is a laser device that irradiates a laser beam that has different absorption characteristics between carious tooth structure and healthy tooth structure and has penetration into the tooth structure. A caries detection device that uses laser light irradiation. (3) The caries detection device applying laser light irradiation according to claim 1, wherein the surface temperature detector is an infrared radiation thermometer or an infrared sensor. (4) The caries detection device applying laser light irradiation according to claim 1, wherein the reflected light detector and/or the transmitted light detector is a laser light sensor such as a thermocouple. (5) A caries detection device applying laser light irradiation as set forth in claim 4, wherein an integrating sphere is attached to the laser light sensor.